Apparatus for supplying glass bodies to glass melters

ABSTRACT

Apparatus is provided for supplying glass to glass melters, the glass specifically being glass bodies in the form of marbles or balls. The marbles are fed by gravity from a hopper to melting units therebelow through flexible supply chutes. Between the hopper and the supply chutes are ejector chutes for ejecting pieces of broken marbles prior to reaching the flexible supply chutes, to avoid jamming therein. The ejector chute has at least one elongate opening extending the length thereof and of a size to pass through broken marbles.

This invention relates to apparatus for supplying glass from a hopper to a glass melting unit, the glass being in the form of marbles or balls.

Glass fibers or filaments are commonly made from streams of molten glass attenuated from orifices in the bottom of an electrically-heated melting unit or bushing. One common technique for producing glass fibers is known as a marble melt process which involves supplying preformed, spherically-shaped bodies of glass, known in the art as marbles, to a unit for melting and conditioning the glass. The molten glass flows in streams through the orifices and the streams are attenuated into filaments or fibers. A plurality of the melting units are commonly used, with several of them being supplied with the glass marbles from a common supply source or hopper.

The marbles used as the glass supply for the melting unit are made in large quantities by marble making-machines and are typically supplied to the location of the marble melting units in three thousand pound barrels. The marbles are then transferred from the barrels to the hoppers which can contain nine hundred pounds of marbles and from there are supplied to the plurality of marble melting units fed by each hopper. The marbles are also usually "graded" prior to being placed in the hopper. Through the handling of the marbles, breakage sometimes results. Further, the marbles will sometimes break in the hopper as they are slightly agitated therein when being fed downwardly therethrough to the bushings. This is particularly true if the marbles are not properly annealed. The fracture of the marble usually occurs after the marbles are scratched which can occur when they are in contact with one another. When the marbles do fracture, they usually do so near the center, with the smaller part of the fractured marble seldom being less than one quarter of it. Stated another way, the marbles usually fracture into two parts, with the two parts usually being in a ratio between one-fourth to three-fourths and one-half to one-half.

The marbles are fed through separate flexible supply chutes from the hopper to the melting units. The flexibility of the supply chutes facilitates the installation of the overall-forming system since each chute can be positioned around auxiliary equipment and supports which the chutes must circumvent in establishing continuous paths from the hopper to the melting units.

One type of flexible supply chute which has heretofore been employed has been made of steel springs or coils of wire, as disclosed in a U.S. Pat. No. 3,867,117 to J. A. Bebart. The springs formed a continuous, flexible supply chute with the openings between the adjacent coils being about one-eighth inch when marbles with one inch diameter were employed. The springs would tend to vibrate as the marbles moved down the chutes and the agitation would aid in moving broken marbles through the chutes. However, on occasion, marble pieces would tend to be caught between the adjacent coils of the wire.

The present invention provides an ejector chute designed to be positioned between the hopper and the flexible supply chute to eject marble pieces prior to entering the supply chute. The ejector chute has at least one elongate opening having a width somewhat smaller than the nominal diameter of the marbles to be employed. This enables broken marble pieces to pass through and yet prevents the smallest size whole marble to be encountered from passing through. In a preferred form, the opening extends in a spiral from one end of the chute to the other with the width being measured from a point on one edge of the opening perpendicularly across to a point on the other edge of the opening. In a further preferred form, the ejector chute is made from at least one spiral wire which forms the chute and extends from one end to the other. More than one such wire can be employed, up to four having been found to be satisfactory, with the greater the number of wires, the greater the pitch thereof to provide the proper width of the openings or spacing between adjacent wires. Additional short wires or prongs can be employed between the main ones at the bottom of the chute; these have been found to substantially prevent the possibility of marbles jamming at the point where they are about to enter the supply chute.

Also in a preferred form, the discharge end of the ejector chute can have an elbow therein with an opening in the outer surface of the elbow through which access can be had to marbles passing through to the supply chute to free any possible jamming in the supply chute or the melting unit.

It is, therefore, a principal object of the invention to provide supply means for supplying glass marbles from a hopper to a melting unit with less jamming resulting therebetween.

Another object of the invention is to provide an ejector chute between a marble hopper and a supply chute having openings through which marble pieces can be ejected prior to entering the supply chute.

A further object of the invention is to provide a glass filament forming system including a hopper and a melting unit with supply means therebetween including a flexible supply chute and an ejector chute for ejecting marble pieces prior to entering the supply chute.

Yet another object of the invention is to provide an ejector chute for removing broken glass marbles passing therethrough, which chute is made from at least one spiral wire forming at least one spiral opening extending from one end of the chute to the other.

Many other objects and advantages of the invention will be apparent from the following detailed description of preferred embodiments thereof, reference being made to the accompanying drawings, in which:

FIG. 1 is a somewhat schematic view in perspective, with parts broken away and with parts in section, of a filament forming system, including a marble hopper, melting units, and supply means therebetween including ejector chutes embodying the invention;

FIG. 2 is an enlarged view in elevation, with parts in section, of a portion of the supply means, including the ejector chute, of FIG. 1;

FIG. 3 is a left side view of the ejector chute of FIG. 2;

FIG. 4 is a side view in elevation of a slightly modified ejector chute embodying the invention;

FIG. 5 is a side view in elevation of another slightly modified ejector chute embodying the invention; and

FIG. 6 is a side view in elevation of a further modified ejector chute embodying the invention.

While the invention is described in connection with a glass filament forming process, it will be evident that the invention can be employed with other glass melting units and is also applicable to other processes in which thermoplastic or other heat-softenable material is supplied to a melter in the form of marbles or balls.

Referring particularly to FIG. 1, melting units or bushings 10 are adapted to contain a supply of molten glass with filaments or fibers 12 formed therebelow by being attenuated from streams of molten glass issuing from bushing tips 14. The filaments can be gathered by suitable means into a strand with the strand then wound about a collecting drum rotatably supported therebelow. The strands also can be collected on a conveyor to form a mat. Each of the melting units 10 is preferably electrically heated and for this purpose the ends of the units have bus-bars 16 connected to power units or transformers 18 located thereabove.

Heat-softenable material or bodies in the form of marbles or balls 20 are fed to the top of each of the melting units 10. Supplying glass material in this form has a number of advantages long known in the art. The marbles, which are formed in large quantities by marble-making machines, are not truly spherical nor are they all entirely of uniform diameter since such precision would be superfluous for producing a supply of glass bodies for melting units. Typically, marbles produced with a nominal diameter of 1 1/32nd inch have actual diameters varying from as small as 3/4 inch up to about 1 1/32nd inch, but with few being over 1 inch in diameter.

After the marbles are formed and annealed, they are transported to the location of the melting units 10 in large, three-thousand pound barrels. The marbles are graded to eliminate those outside the range of diameters for any given nominal diameter and are then supplied to a hopper 22 which can contain as much as nine hundred pounds of the marbles 20. The hopper 22 has elongate openings or slots 24 in the bottom thereof below which is a reciprocating slide 26 which is slidably supported in a guide housing 28 below the hopper bottom. The slide 26 has openings 30 extending therethrough with each of the openings 30 being in register with one of the slots 24. The slide 26 has a stroke which is less than the length of the slots 24 so that the openings 30 always communicate with the slots 24 and the marbles cannot jam between the edges of the slots and the openings 30. By way of example, the stroke of the slide 26 is 5 inches while the length of the slot 24 is 8 inches. A discharge tube 32 (FIG. 2) is aligned with each of the openings 30 of the slide 26 and is affixed to the slide so as to reciprocate therewith. The tubes can extend through suitable slots (not shown) located in the bottom of the guide housing 28.

Supply means indicated at 34 connect each of the melting units 10 with the hopper 22 and specifically with the discharge tubes 32. Each of the supply means 34 includes a flexible supply chute 36 and an ejector chute 38. The supply chute 36 can be the same as that shown and described in the aforementioned U.S. Pat. No. 3,867,117. By way of example, the chute can be made of a coil of wire 40, No. 12 wire being satisfactory, the pitch or spacing between adjacent turns of which can be 1/8 inch for marbles having a nominal diameter of 1 or 1 1/32nd inch. The wire 40 extends all the way from the ejector chute 38 to a discharge nipple 42 located at the top of the melting unit 10.

The flexible nature of the chute 36 enables it to be readily positioned around auxiliary items such as the transformer 18 as well as various supporting frames (not shown). The entire chute 36, as well as the ejector chute 38, are continually filled with marbles which are sequentially fed to the melting units as the marbles therein are melted. The intermittent movement of the marbles through the wire 40, along with the reciprocating movement of the discharge tubes 32, induce vibrations in the wire 40 which are effective to urge the marbles through the chute, even including some imperfectly shaped marbles and partially broken ones. The vibrational agitation can even help move the marbles up a slight grade in the chute 36 without disruption of the marble flow. However, on occasion, pieces of broken marbles and particularly thinner pieces known as shards can stick in the spacing between the turns of the wire 40 and cause jamming.

To further reduce the possibility of jamming of the marbles in their movement from the hopper 22 to the units 10, the ejector chutes 38 are employed to eliminate pieces or shards of broken marbles prior to reaching the supply chute 36. The breakage of the marbles during their handling is not uncommon since the marbles are supplied to the large drums, are graded, and are subsequently dumped into the hopper 22. Some agitation of the marbles 20 in the hopper 22 also occurs due to the reciprocatory motion of the slide 26. When the marbles are in contact with one another and move relative to one another, scratching of the surfaces can result and breaking then frequently occurs. Breaking is particularly frequent if the marbles have not been properly annealed. When the marbles do break or fracture they usually do so near the center, with the smaller part of the fractured marble seldom being less than one quarter of it. Thus, when a marble fractures into two pieces or parts, the ratio of the smallest to the largest part is usually between one-fourth to three-fourths and one-half to one-half. When thinner parts or shards result, the remaining larger part is sufficiently round or whole that it can move through the supply chute 36 with little difficulty. At the same time, the thin part or shard can be readily disposed of by the ejector chute 38.

Referring to FIGS. 2 and 3, the ejector chute 38 includes an entrance connection 44 having an upper threaded end 46 turned into a threaded ring 48 which is rotatably mounted on the discharge tube 32 through cooperating flanges. The ejector chute 38 also includes a discharge connection 50 at its lower end. A spiral or helical member or wire 52 extends the length of the chute 38 between the entrance connection 44 and the discharge connection 50, being suitably connected to both, as by welding. The member 52 can be of 1/8 inch diameter wire, which is stiffer than the wire 40 of the chute 36. The helical member 52 forms a helical space or opening throughout the length of the discharge chute 38 between the entrance and discharge connections. The width of the opening is measured from a point on one edge of the opening perpendicularly across to a point on the other edge of the opening, the edges being formed by the closest surfaces on the adjacent turns of the member 52. With a single helical wire, the width of the opening approximately equals the pitch of the wire.

With the aforementioned marbles having a 1 1/32 inch diameter, the bore of the ejector passage for the aforementioned marbles can be from 1 1/16th to 1 1/2 times the nominal diameter. The width of the spiral or transverse opening or openings, as indicated by the arrows in FIG. 3, preferably is from 49/64ths to 55/64ths inch. The width also can be from 4 to 8 times the pitch of the spiral member 40 forming the supply chute 36. The width also is smaller than the diameter of the smallest marble expected to be encountered and larger than 50% of that diameter, and is about 65% to 90 %, preferably 80% to 85%, of the diameter of the smallest marble expected to be encountered for marbles of any given nominal diameter. This spacing enables the proper ejection of marble pieces which tend to be squeezed through the transverse opening by whole marbles on each side thereof (FIG. 2). Marble pieces too large to pass through the opening are sufficiently round to move satisfactorily through the supply chute 36.

An additional helical or spiral member or prong 54 is located at the lower end of the elongate member 52. The prong 54 is affixed to the upper end of the discharge connection 50 and extends, in this instance, through half of a turn, having the same pitch as the member 52. This, then, reduces the width of the opening at the lower end of the chute to about half of the rest of the spiral opening thereabove. The prong helps in guiding the whole marbles to the center of the bore of the chute 38 and specifically the bore of the discharge connection 50. This is particularly effective for very small or deformed marbles which otherwise may jam at the top of the connection 50.

The discharge connection 50 is in the form of a 90° elbow with the wire 40 of the supply chute 36 received over the lower end of the connection and suitably affixed thereto, again as by welding. The outer surface of the elbow 50 has an elongate opening 56 formed therein with two curved bars 58 extending thereover. The bars 58 prevent the possibility of the marbles 20 passing through the opening 56 while the opening 56 still is sufficiently large to provide access by an operator particularly to marbles in the chute 36. In the event that jamming might occur in the supply chute 36 or in the upper portion of the melting unit 10, the operator can then push on the marbles entering the supply chute 36 and clear the jam. Also, smaller pieces of marble not discharged through the spiral opening of the ejector chute 38 can be ejected between the bars 58.

A slightly modified ejector chute 60 is shown in FIG. 4. The ejector chute 60 includes the entrance connection 44 and the discharge connection 50. In this instance, two spiral or helical members or wires 62 and 64 form two transverse or spiral openings over the length of the ejector chute 60 between the entrance and discharge ends. The width of the openings is then measured between adjacent turns of the wires 62 and 64 with the width of the opening being roughly half the pitch of each of the wires 62 and 64. Two prongs 66 and 68 are located at the lower end of the chute, being affixed to the upper end of the discharge connection 50 and reducing the width of the openings at the lower end to one-half of the openings thereabove. Each of the prongs 66 and 68 extends about one-half turn and they serve the same purpose as the prong 54 of the chute 38.

An ejector chute 70 of FIG. 5 is similar to the chute 60 but has three spiral or helical members or wires 72, 74, and 76 extending the length of the chute 70 between the entrance and discharge connections. Three spiral openings are formed by the three members in this instance, with the width of each opening being the same as the width of the openings of the chutes 38 and 60, being roughly equal to one-third the pitch of each of the members 72-76. Three prongs 78, 80, and 82 are affixed to the discharge connection 50 and extend upwardly therefrom again to reduce the width of the openings at the lower end of the chute to about one-half that of the upper portions of the openings. In this instance, each of the prongs extends through about one-third of a turn of the members 72-76.

An ejector chute 84 of FIG. 6 includes the entrance and discharge connections 44 and 50, as before. In this instance, four spiral or helical members or wires 86, 88, 90, and 92 form four elongate or spiral openings between the ends of the chute 84. The openings again have widths the same as those of the chutes 70, 60, and 38 which, in this instance, are equal to about one-fourth of the pitch of the members 86-92. Four prongs 94, 96, 98, and 100 extend upwardly from the upper end of the discharge connection 50 and again reduce the width of the lower portions of the spiral openings to about one-half of that of the upper portions of the openings. The prongs 94-100, in this instance, extend only about one-fourth of a turn of the wires 86-92.

It will be noted that in all instances the wires or elongate members of the discharge chute are parallel and equally spaced to form openings of uniform width throughout the length of the chutes. While all of the chutes discussed above have performed satisfactorily, the low or small pitch of the helical member 52 of the chute 38 sometimes tends to cause a broken marble to wedge between the adjacent turns which is less apt to occur with the longer pitch of the members of the chutes of FIGS. 4-6.

It will be readily understood that the pitch of the wires and the widths of the openings and the bore of the ejector chute can be changed by moving the entrance connection 44 and the discharge connection 50 toward and away from one another. Also, twisting of the one connection relative to the other can similarly change the opening width and increase or decrease the bore of the ejector chute.

Various modifications of the above-described embodiments of the invention will be apparent to those skilled in the art and it is to be understood that such modifications can be made without departing from the scope an the invention, if they are within the spirit and the tenor of the accompanying claims. 

I claim:
 1. Apparatus for producing glass filaments comprising a marble hopper, a bushing, and means for feeding glass marbles sequentially from said hopper to said bushing, said bushing comprising means for melting the glass marbles and means for attenuating the molten glass into filaments, said feeding means comprising a conduit for generally spherical objects comprising a plurality of substantially coaxial helically wound wires, the wires being spaced apart by an ejector opening.
 2. The apparatus of claim 1 in which said ejector opening extends substantially along the entire length of said conduit.
 3. The apparatus of claim 2 in which said ejector opening has a width within the range of from about 65 to about 90% of the smallest diameter marbles expected to be encountered for a given nominal diameter of marbles.
 4. The apparatus of claim 1 comprising an additional short wire positioned at the bottom of said conduit within said ejector opening.
 5. The apparatus of claim 1 comprising an elbow surrounding a portion of said conduit, said elbow having an access opening.
 6. The apparatus of claim 5 in which said access opening does not exceed the width of said ejector opening. 